Ask: Why Won't My Mac Sleep Properly?

Got an Apple, Mac, or iOS tech question? We have the answer. In this week's installment of Ask, we'll take a look at issues that may prevent your Mac from properly entering sleep mode.

Question: I have a late 2012 iMac running Mountain Lion, and I’ve been having trouble with my computer entering sleep mode recently. It’s supposed to go to sleep after 30 minutes of inactivity, but sometimes it simply doesn’t do it. Other times it wakes up from sleep mode automatically, and I come home to discover that the computer has come to life without me doing anything. Any ideas?

Answer: There could be several things that are causing your Mac to wake up, or not go to sleep, and it can be a bit difficult to troubleshoot this issue to find out what that cause might be.

Apple does, however, provide a Knowledge Base article on the issue. This is an attempt to help users pick the solution for their particular situation and ensure that all settings are properly enabled. It should help your computer to both sleep properly and stay asleep when you want it to. Here are some of the highlights of the note:

> Energy-saving preferences could be set improperly. Ensure that when you go to System Preferences > Energy Saver, that the slider for setting the computer’s sleep setting is set the way you wish.

> Other users could be waking the machine remotely using shared resources. Ensure that if you connect to your computer using network access that you disconnect in order for the computer to go to sleep. You can disable network wake by going to System Preferences > Energy Saver, and unchecking the option for “Wake for Wi-Fi Network Access.”

> Bluetooth devices such as keyboards and mice can wake your computer if a key or button is pressed. Try switching off these Bluetooth peripherals when your Mac is not in use.

Comment

I know someone who has an older iMac (mid 00’s) and it wakes from sleep every time the light in the closest bathroom is turned on. This is in a home that has older wiring with circuits that feed multiple rooms.